Hebe News – Article 1
Another Cold Spell
Over the last ten years or so, during which time we have been raising quite large numbers of hebes in pots in connection with show exhibits, we have become resigned to losing a proportion each year. The losses occur mainly through mildew and other fungal infections which seem to take their toll, regardless of what spraying regime we adopt, mostly during the summer months.
Losses are usually at an acceptably low level which, taken over the year, are no more than some 5% of a total annual production of 500 or so plants which have survived beyond the first potting-on stage. However, over the last two years, losses during the winter have been considerably higher than we normally expect, as a result of (for central southern England) unusually lengthy cold spells with lying snow.
Just over a year ago, I wrote an article for Hebe News (Volume 24, Number 1, pages 10–11) in which I expressed my surprise at the extent to which many of what I would consider to be fairly tender hebes (in pots) had survived, without any protection, a fairly lengthy spell of cold weather in late December and early January, with temperatures down to –10°C.
As it turned out, my pleasure at this turn of events was to be short-lived. On February 2nd 2009 an unexpected 30 cm (1 ft) of snow fell in Farnham in less than 3 hours, and this hung around for several days, although minimum temperatures were never as low as they had been in the immediately preceding cold weather. At this point, many of the half-hardy hebes in pots, which had survived the earlier cold spell, lost the will to live, and some 200 plants were eventually thrown away. None of the garden hebes were actually lost as a result of the cold spell, although several showed signs of severe frost burn.
So far, over the winter of 2009–2010, we don’t seem to have experienced quite such consistently low day and night temperatures as we did last winter, but it has nevertheless been quite chilly, with minimum night temperatures on occasions falling as low as –9°C and frosts on most nights in January. On 5th January 2010 we had a fall of 30 cm (1 ft) of snow, which had only just started to melt when another 7 cm (3 in) followed a week later, with the whole lot eventually taking a further week to melt. As in the previous winter, we found that half-hardy hebes, both in pots and in the ground, suffered more damage after being covered by snow than had previously arisen from exposure to low temperatures alone.
Cultivars in pots which suffered extensive losses this winter included several of the Wiri series (Hebe ‘Wiri Joy’, Hebe ‘Wiri Charm’, Hebe ‘Wiri Prince’ and Hebe ‘Wiri Vision’), Hebe ‘Headfortii’, Hebe ‘Inspiration’, Hebe ‘Louise’, Hebe ‘Hanne’, Hebe ‘Maria’, Hebe ‘Paula’, Hebe ‘Simon Delaux’ and Hebe ‘Veitchii’.
We also lost nearly all our Hebe ‘Franciscana Variegata’, some of which had survived previous winters with no damage at all, together with most examples of a form of Hebe diosmifolia which has always been rather prone to frost damage.
In the garden we have a number of very sick plants and I suspect that many of them may not survive. These include Hebe ‘Champagne’, Hebe ‘Hanne’, Hebe ‘Wiri Joy’, Hebe ‘Wiri Image’, Hebe ‘Wiri Charm’ and Hebe ‘Fragrant Jewel’. Some, but not all of our Hebe ‘Amy’, Hebe ‘Great Orme’, Hebe macrocarpa var macrocarpa, Hebe ‘Blue Star’, Hebe ‘Patti Dossett’, Hebe ‘Reine des Blanches’ and Hebe ‘Icing Sugar’ have also been quite badly affected. These are all varieties which have, on the whole, come unscathed through several earlier winters. However, they have not previously been covered with snow for as long as was the case this year. We shall cut these back hard once the weather improves and, with luck, they will put on new growth in the spring. Hebe ‘Marie Antoinette’, which had flowered profusely in the garden for the first time last summer, is looking very dead indeed, but some of the potted plants of this cultivar look as though they might well survive.
Losses on the scale which we have experienced over the last two winters are particularly disappointing, even though we have always recognised that we have been taking a chance by growing tender varieties without any protection. Rather than abandoning production of half-hardy hebes altogether, an option which we have seriously considered, we shall try to reduce next winter’s losses through growing a smaller proportion of tender hebes, and locating over-wintered pots against walls and hedges to provide some shelter, particularly from snow. We shall probably also give some additional protection by covering with horticultural fleece.
Perhaps we should look on the bright side and take the view that our experience over the last two winters has improved our knowledge of which half-hardy hebe varieties are unlikely to survive a moderately hard winter in the south of England.
Gordon and Ginny Smith
Registered Charity No 801398
